crypto/openssh/sshconnect2.c

   1 /* $OpenBSD: sshconnect2.c,v 1.204 2014/02/02 03:44:32 djm Exp $ */
   2 /* $FreeBSD$ */
   3 /*
   4  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
   5  * Copyright (c) 2008 Damien Miller.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26  */
  27
  28 #include "includes.h"
  29
  30 #include <sys/types.h>
  31 #include <sys/socket.h>
  32 #include <sys/wait.h>
  33 #include <sys/stat.h>
  34
  35 #include <errno.h>
  36 #include <fcntl.h>
  37 #include <netdb.h>
  38 #include <pwd.h>
  39 #include <signal.h>
  40 #include <stdarg.h>
  41 #include <stdio.h>
  42 #include <string.h>
  43 #include <unistd.h>
  44 #if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H) && !defined(BROKEN_STRNVIS)
  45 #include <vis.h>
  46 #endif
  47
  48 #include "openbsd-compat/sys-queue.h"
  49
  50 #include "xmalloc.h"
  51 #include "ssh.h"
  52 #include "ssh2.h"
  53 #include "buffer.h"
  54 #include "packet.h"
  55 #include "compat.h"
  56 #include "cipher.h"
  57 #include "key.h"
  58 #include "kex.h"
  59 #include "myproposal.h"
  60 #include "sshconnect.h"
  61 #include "authfile.h"
  62 #include "dh.h"
  63 #include "authfd.h"
  64 #include "log.h"
  65 #include "readconf.h"
  66 #include "misc.h"
  67 #include "match.h"
  68 #include "dispatch.h"
  69 #include "canohost.h"
  70 #include "msg.h"
  71 #include "pathnames.h"
  72 #include "uidswap.h"
  73 #include "hostfile.h"
  74
  75 #ifdef GSSAPI
  76 #include "ssh-gss.h"
  77 #endif
  78
  79 /* import */
  80 extern char *client_version_string;
  81 extern char *server_version_string;
  82 extern Options options;
  83 #ifdef  NONE_CIPHER_ENABLED
  84 extern Kex *xxx_kex;
  85
  86 /*
  87  * tty_flag is set in ssh.c so we can use it here.  If set then prevent
  88  * the switch to the null cipher.
  89  */
  90
  91 extern int tty_flag;
  92 #endif
  93
  94 /*
  95  * SSH2 key exchange
  96  */
  97
  98 u_char *session_id2 = NULL;
  99 u_int session_id2_len = 0;
 100
 101 char *xxx_host;
 102 struct sockaddr *xxx_hostaddr;
 103
 104 Kex *xxx_kex = NULL;
 105
 106 static int
 107 verify_host_key_callback(Key *hostkey)
 108 {
 109         if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1)
 110                 fatal("Host key verification failed.");
 111         return 0;
 112 }
 113
 114 static char *
 115 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port)
 116 {
 117         char *oavail, *avail, *first, *last, *alg, *hostname, *ret;
 118         size_t maxlen;
 119         struct hostkeys *hostkeys;
 120         int ktype;
 121         u_int i;
 122
 123         /* Find all hostkeys for this hostname */
 124         get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL);
 125         hostkeys = init_hostkeys();
 126         for (i = 0; i < options.num_user_hostfiles; i++)
 127                 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]);
 128         for (i = 0; i < options.num_system_hostfiles; i++)
 129                 load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]);
 130
 131         oavail = avail = xstrdup(KEX_DEFAULT_PK_ALG);
 132         maxlen = strlen(avail) + 1;
 133         first = xmalloc(maxlen);
 134         last = xmalloc(maxlen);
 135         *first = *last = '\0';
 136
 137 #define ALG_APPEND(to, from) \
 138         do { \
 139                 if (*to != '\0') \
 140                         strlcat(to, ",", maxlen); \
 141                 strlcat(to, from, maxlen); \
 142         } while (0)
 143
 144         while ((alg = strsep(&avail, ",")) && *alg != '\0') {
 145                 if ((ktype = key_type_from_name(alg)) == KEY_UNSPEC)
 146                         fatal("%s: unknown alg %s", __func__, alg);
 147                 if (lookup_key_in_hostkeys_by_type(hostkeys,
 148                     key_type_plain(ktype), NULL))
 149                         ALG_APPEND(first, alg);
 150                 else
 151                         ALG_APPEND(last, alg);
 152         }
 153 #undef ALG_APPEND
 154         xasprintf(&ret, "%s%s%s", first, *first == '\0' ? "" : ",", last);
 155         if (*first != '\0')
 156                 debug3("%s: prefer hostkeyalgs: %s", __func__, first);
 157
 158         free(first);
 159         free(last);
 160         free(hostname);
 161         free(oavail);
 162         free_hostkeys(hostkeys);
 163
 164         return ret;
 165 }
 166
 167 void
 168 ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port)
 169 {
 170         Kex *kex;
 171
 172         xxx_host = host;
 173         xxx_hostaddr = hostaddr;
 174
 175         if (options.ciphers == (char *)-1) {
 176                 logit("No valid ciphers for protocol version 2 given, using defaults.");
 177                 options.ciphers = NULL;
 178         }
 179         if (options.ciphers != NULL) {
 180                 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 181                 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
 182         }
 183         myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 184             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
 185         myproposal[PROPOSAL_ENC_ALGS_STOC] =
 186             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
 187         if (options.compression) {
 188                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 189                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none";
 190         } else {
 191                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 192                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib";
 193         }
 194         if (options.macs != NULL) {
 195                 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
 196                 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
 197         }
 198         if (options.hostkeyalgorithms != NULL)
 199                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 200                     compat_pkalg_proposal(options.hostkeyalgorithms);
 201         else {
 202                 /* Prefer algorithms that we already have keys for */
 203                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 204                     compat_pkalg_proposal(
 205                     order_hostkeyalgs(host, hostaddr, port));
 206         }
 207         if (options.kex_algorithms != NULL)
 208                 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms;
 209         myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(
 210             myproposal[PROPOSAL_KEX_ALGS]);
 211
 212         if (options.rekey_limit || options.rekey_interval)
 213                 packet_set_rekey_limits((u_int32_t)options.rekey_limit,
 214                     (time_t)options.rekey_interval);
 215
 216         /* start key exchange */
 217         kex = kex_setup(myproposal);
 218         kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
 219         kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
 220         kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
 221         kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
 222         kex->kex[KEX_ECDH_SHA2] = kexecdh_client;
 223         kex->kex[KEX_C25519_SHA256] = kexc25519_client;
 224         kex->client_version_string=client_version_string;
 225         kex->server_version_string=server_version_string;
 226         kex->verify_host_key=&verify_host_key_callback;
 227
 228         xxx_kex = kex;
 229
 230         dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
 231
 232         if (options.use_roaming && !kex->roaming) {
 233                 debug("Roaming not allowed by server");
 234                 options.use_roaming = 0;
 235         }
 236
 237         session_id2 = kex->session_id;
 238         session_id2_len = kex->session_id_len;
 239
 240 #ifdef DEBUG_KEXDH
 241         /* send 1st encrypted/maced/compressed message */
 242         packet_start(SSH2_MSG_IGNORE);
 243         packet_put_cstring("markus");
 244         packet_send();
 245         packet_write_wait();
 246 #endif
 247 }
 248
 249 /*
 250  * Authenticate user
 251  */
 252
 253 typedef struct Authctxt Authctxt;
 254 typedef struct Authmethod Authmethod;
 255 typedef struct identity Identity;
 256 typedef struct idlist Idlist;
 257
 258 struct identity {
 259         TAILQ_ENTRY(identity) next;
 260         AuthenticationConnection *ac;   /* set if agent supports key */
 261         Key     *key;                   /* public/private key */
 262         char    *filename;              /* comment for agent-only keys */
 263         int     tried;
 264         int     isprivate;              /* key points to the private key */
 265         int     userprovided;
 266 };
 267 TAILQ_HEAD(idlist, identity);
 268
 269 struct Authctxt {
 270         const char *server_user;
 271         const char *local_user;
 272         const char *host;
 273         const char *service;
 274         Authmethod *method;
 275         sig_atomic_t success;
 276         char *authlist;
 277         /* pubkey */
 278         Idlist keys;
 279         AuthenticationConnection *agent;
 280         /* hostbased */
 281         Sensitive *sensitive;
 282         /* kbd-interactive */
 283         int info_req_seen;
 284         /* generic */
 285         void *methoddata;
 286 };
 287 struct Authmethod {
 288         char    *name;          /* string to compare against server's list */
 289         int     (*userauth)(Authctxt *authctxt);
 290         void    (*cleanup)(Authctxt *authctxt);
 291         int     *enabled;       /* flag in option struct that enables method */
 292         int     *batch_flag;    /* flag in option struct that disables method */
 293 };
 294
 295 void    input_userauth_success(int, u_int32_t, void *);
 296 void    input_userauth_success_unexpected(int, u_int32_t, void *);
 297 void    input_userauth_failure(int, u_int32_t, void *);
 298 void    input_userauth_banner(int, u_int32_t, void *);
 299 void    input_userauth_error(int, u_int32_t, void *);
 300 void    input_userauth_info_req(int, u_int32_t, void *);
 301 void    input_userauth_pk_ok(int, u_int32_t, void *);
 302 void    input_userauth_passwd_changereq(int, u_int32_t, void *);
 303
 304 int     userauth_none(Authctxt *);
 305 int     userauth_pubkey(Authctxt *);
 306 int     userauth_passwd(Authctxt *);
 307 int     userauth_kbdint(Authctxt *);
 308 int     userauth_hostbased(Authctxt *);
 309
 310 #ifdef GSSAPI
 311 int     userauth_gssapi(Authctxt *authctxt);
 312 void    input_gssapi_response(int type, u_int32_t, void *);
 313 void    input_gssapi_token(int type, u_int32_t, void *);
 314 void    input_gssapi_hash(int type, u_int32_t, void *);
 315 void    input_gssapi_error(int, u_int32_t, void *);
 316 void    input_gssapi_errtok(int, u_int32_t, void *);
 317 #endif
 318
 319 void    userauth(Authctxt *, char *);
 320
 321 static int sign_and_send_pubkey(Authctxt *, Identity *);
 322 static void pubkey_prepare(Authctxt *);
 323 static void pubkey_cleanup(Authctxt *);
 324 static Key *load_identity_file(char *, int);
 325
 326 static Authmethod *authmethod_get(char *authlist);
 327 static Authmethod *authmethod_lookup(const char *name);
 328 static char *authmethods_get(void);
 329
 330 Authmethod authmethods[] = {
 331 #ifdef GSSAPI
 332         {"gssapi-with-mic",
 333                 userauth_gssapi,
 334                 NULL,
 335                 &options.gss_authentication,
 336                 NULL},
 337 #endif
 338         {"hostbased",
 339                 userauth_hostbased,
 340                 NULL,
 341                 &options.hostbased_authentication,
 342                 NULL},
 343         {"publickey",
 344                 userauth_pubkey,
 345                 NULL,
 346                 &options.pubkey_authentication,
 347                 NULL},
 348         {"keyboard-interactive",
 349                 userauth_kbdint,
 350                 NULL,
 351                 &options.kbd_interactive_authentication,
 352                 &options.batch_mode},
 353         {"password",
 354                 userauth_passwd,
 355                 NULL,
 356                 &options.password_authentication,
 357                 &options.batch_mode},
 358         {"none",
 359                 userauth_none,
 360                 NULL,
 361                 NULL,
 362                 NULL},
 363         {NULL, NULL, NULL, NULL, NULL}
 364 };
 365
 366 void
 367 ssh_userauth2(const char *local_user, const char *server_user, char *host,
 368     Sensitive *sensitive)
 369 {
 370         Authctxt authctxt;
 371         int type;
 372
 373         if (options.challenge_response_authentication)
 374                 options.kbd_interactive_authentication = 1;
 375
 376         packet_start(SSH2_MSG_SERVICE_REQUEST);
 377         packet_put_cstring("ssh-userauth");
 378         packet_send();
 379         debug("SSH2_MSG_SERVICE_REQUEST sent");
 380         packet_write_wait();
 381         type = packet_read();
 382         if (type != SSH2_MSG_SERVICE_ACCEPT)
 383                 fatal("Server denied authentication request: %d", type);
 384         if (packet_remaining() > 0) {
 385                 char *reply = packet_get_string(NULL);
 386                 debug2("service_accept: %s", reply);
 387                 free(reply);
 388         } else {
 389                 debug2("buggy server: service_accept w/o service");
 390         }
 391         packet_check_eom();
 392         debug("SSH2_MSG_SERVICE_ACCEPT received");
 393
 394         if (options.preferred_authentications == NULL)
 395                 options.preferred_authentications = authmethods_get();
 396
 397         /* setup authentication context */
 398         memset(&authctxt, 0, sizeof(authctxt));
 399         pubkey_prepare(&authctxt);
 400         authctxt.server_user = server_user;
 401         authctxt.local_user = local_user;
 402         authctxt.host = host;
 403         authctxt.service = "ssh-connection";            /* service name */
 404         authctxt.success = 0;
 405         authctxt.method = authmethod_lookup("none");
 406         authctxt.authlist = NULL;
 407         authctxt.methoddata = NULL;
 408         authctxt.sensitive = sensitive;
 409         authctxt.info_req_seen = 0;
 410         if (authctxt.method == NULL)
 411                 fatal("ssh_userauth2: internal error: cannot send userauth none request");
 412
 413         /* initial userauth request */
 414         userauth_none(&authctxt);
 415
 416         dispatch_init(&input_userauth_error);
 417         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
 418         dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
 419         dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
 420         dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt);     /* loop until success */
 421
 422         pubkey_cleanup(&authctxt);
 423         dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
 424
 425 #ifdef  NONE_CIPHER_ENABLED
 426         /*
 427          * If the user explicitly requests to use the none cipher enable it
 428          * post authentication and only if the right conditions are met: both
 429          * of the NONE switches must be true and there must be no tty allocated.
 430          */
 431         if (options.none_switch == 1 && options.none_enabled == 1) {
 432                 if (!tty_flag) {
 433                         debug("Requesting none cipher re-keying...");
 434                         myproposal[PROPOSAL_ENC_ALGS_STOC] = "none";
 435                         myproposal[PROPOSAL_ENC_ALGS_CTOS] = "none";
 436                         kex_prop2buf(&xxx_kex->my, myproposal);
 437                         packet_request_rekeying();
 438                         fprintf(stderr, "WARNING: enabled NONE cipher\n");
 439                 } else {
 440                         /* Requested NONE cipher on an interactive session. */
 441                         debug("Cannot switch to NONE cipher with tty "
 442                             "allocated");
 443                         fprintf(stderr, "NONE cipher switch disabled given "
 444                             "a TTY is allocated\n");
 445                 }
 446         }
 447 #endif
 448         debug("Authentication succeeded (%s).", authctxt.method->name);
 449 }
 450
 451 void
 452 userauth(Authctxt *authctxt, char *authlist)
 453 {
 454         if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
 455                 authctxt->method->cleanup(authctxt);
 456
 457         free(authctxt->methoddata);
 458         authctxt->methoddata = NULL;
 459         if (authlist == NULL) {
 460                 authlist = authctxt->authlist;
 461         } else {
 462                 free(authctxt->authlist);
 463                 authctxt->authlist = authlist;
 464         }
 465         for (;;) {
 466                 Authmethod *method = authmethod_get(authlist);
 467                 if (method == NULL)
 468                         fatal("Permission denied (%s).", authlist);
 469                 authctxt->method = method;
 470
 471                 /* reset the per method handler */
 472                 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
 473                     SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
 474
 475                 /* and try new method */
 476                 if (method->userauth(authctxt) != 0) {
 477                         debug2("we sent a %s packet, wait for reply", method->name);
 478                         break;
 479                 } else {
 480                         debug2("we did not send a packet, disable method");
 481                         method->enabled = NULL;
 482                 }
 483         }
 484 }
 485
 486 /* ARGSUSED */
 487 void
 488 input_userauth_error(int type, u_int32_t seq, void *ctxt)
 489 {
 490         fatal("input_userauth_error: bad message during authentication: "
 491             "type %d", type);
 492 }
 493
 494 /* ARGSUSED */
 495 void
 496 input_userauth_banner(int type, u_int32_t seq, void *ctxt)
 497 {
 498         char *msg, *raw, *lang;
 499         u_int len;
 500
 501         debug3("input_userauth_banner");
 502         raw = packet_get_string(&len);
 503         lang = packet_get_string(NULL);
 504         if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) {
 505                 if (len > 65536)
 506                         len = 65536;
 507                 msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */
 508                 strnvis(msg, raw, len * 4 + 1, VIS_SAFE|VIS_OCTAL|VIS_NOSLASH);
 509                 fprintf(stderr, "%s", msg);
 510                 free(msg);
 511         }
 512         free(raw);
 513         free(lang);
 514 }
 515
 516 /* ARGSUSED */
 517 void
 518 input_userauth_success(int type, u_int32_t seq, void *ctxt)
 519 {
 520         Authctxt *authctxt = ctxt;
 521
 522         if (authctxt == NULL)
 523                 fatal("input_userauth_success: no authentication context");
 524         free(authctxt->authlist);
 525         authctxt->authlist = NULL;
 526         if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
 527                 authctxt->method->cleanup(authctxt);
 528         free(authctxt->methoddata);
 529         authctxt->methoddata = NULL;
 530         authctxt->success = 1;                  /* break out */
 531 }
 532
 533 void
 534 input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt)
 535 {
 536         Authctxt *authctxt = ctxt;
 537
 538         if (authctxt == NULL)
 539                 fatal("%s: no authentication context", __func__);
 540
 541         fatal("Unexpected authentication success during %s.",
 542             authctxt->method->name);
 543 }
 544
 545 /* ARGSUSED */
 546 void
 547 input_userauth_failure(int type, u_int32_t seq, void *ctxt)
 548 {
 549         Authctxt *authctxt = ctxt;
 550         char *authlist = NULL;
 551         int partial;
 552
 553         if (authctxt == NULL)
 554                 fatal("input_userauth_failure: no authentication context");
 555
 556         authlist = packet_get_string(NULL);
 557         partial = packet_get_char();
 558         packet_check_eom();
 559
 560         if (partial != 0) {
 561                 logit("Authenticated with partial success.");
 562                 /* reset state */
 563                 pubkey_cleanup(authctxt);
 564                 pubkey_prepare(authctxt);
 565         }
 566         debug("Authentications that can continue: %s", authlist);
 567
 568         userauth(authctxt, authlist);
 569 }
 570
 571 /* ARGSUSED */
 572 void
 573 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt)
 574 {
 575         Authctxt *authctxt = ctxt;
 576         Key *key = NULL;
 577         Identity *id = NULL;
 578         Buffer b;
 579         int pktype, sent = 0;
 580         u_int alen, blen;
 581         char *pkalg, *fp;
 582         u_char *pkblob;
 583
 584         if (authctxt == NULL)
 585                 fatal("input_userauth_pk_ok: no authentication context");
 586         if (datafellows & SSH_BUG_PKOK) {
 587                 /* this is similar to SSH_BUG_PKAUTH */
 588                 debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
 589                 pkblob = packet_get_string(&blen);
 590                 buffer_init(&b);
 591                 buffer_append(&b, pkblob, blen);
 592                 pkalg = buffer_get_string(&b, &alen);
 593                 buffer_free(&b);
 594         } else {
 595                 pkalg = packet_get_string(&alen);
 596                 pkblob = packet_get_string(&blen);
 597         }
 598         packet_check_eom();
 599
 600         debug("Server accepts key: pkalg %s blen %u", pkalg, blen);
 601
 602         if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
 603                 debug("unknown pkalg %s", pkalg);
 604                 goto done;
 605         }
 606         if ((key = key_from_blob(pkblob, blen)) == NULL) {
 607                 debug("no key from blob. pkalg %s", pkalg);
 608                 goto done;
 609         }
 610         if (key->type != pktype) {
 611                 error("input_userauth_pk_ok: type mismatch "
 612                     "for decoded key (received %d, expected %d)",
 613                     key->type, pktype);
 614                 goto done;
 615         }
 616         fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
 617         debug2("input_userauth_pk_ok: fp %s", fp);
 618         free(fp);
 619
 620         /*
 621          * search keys in the reverse order, because last candidate has been
 622          * moved to the end of the queue.  this also avoids confusion by
 623          * duplicate keys
 624          */
 625         TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
 626                 if (key_equal(key, id->key)) {
 627                         sent = sign_and_send_pubkey(authctxt, id);
 628                         break;
 629                 }
 630         }
 631 done:
 632         if (key != NULL)
 633                 key_free(key);
 634         free(pkalg);
 635         free(pkblob);
 636
 637         /* try another method if we did not send a packet */
 638         if (sent == 0)
 639                 userauth(authctxt, NULL);
 640 }
 641
 642 #ifdef GSSAPI
 643 int
 644 userauth_gssapi(Authctxt *authctxt)
 645 {
 646         Gssctxt *gssctxt = NULL;
 647         static gss_OID_set gss_supported = NULL;
 648         static u_int mech = 0;
 649         OM_uint32 min;
 650         int ok = 0;
 651
 652         /* Try one GSSAPI method at a time, rather than sending them all at
 653          * once. */
 654
 655         if (gss_supported == NULL)
 656                 gss_indicate_mechs(&min, &gss_supported);
 657
 658         /* Check to see if the mechanism is usable before we offer it */
 659         while (mech < gss_supported->count && !ok) {
 660                 /* My DER encoding requires length<128 */
 661                 if (gss_supported->elements[mech].length < 128 &&
 662                     ssh_gssapi_check_mechanism(&gssctxt,
 663                     &gss_supported->elements[mech], authctxt->host)) {
 664                         ok = 1; /* Mechanism works */
 665                 } else {
 666                         mech++;
 667                 }
 668         }
 669
 670         if (!ok)
 671                 return 0;
 672
 673         authctxt->methoddata=(void *)gssctxt;
 674
 675         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 676         packet_put_cstring(authctxt->server_user);
 677         packet_put_cstring(authctxt->service);
 678         packet_put_cstring(authctxt->method->name);
 679
 680         packet_put_int(1);
 681
 682         packet_put_int((gss_supported->elements[mech].length) + 2);
 683         packet_put_char(SSH_GSS_OIDTYPE);
 684         packet_put_char(gss_supported->elements[mech].length);
 685         packet_put_raw(gss_supported->elements[mech].elements,
 686             gss_supported->elements[mech].length);
 687
 688         packet_send();
 689
 690         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
 691         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
 692         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
 693         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
 694
 695         mech++; /* Move along to next candidate */
 696
 697         return 1;
 698 }
 699
 700 static OM_uint32
 701 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok)
 702 {
 703         Authctxt *authctxt = ctxt;
 704         Gssctxt *gssctxt = authctxt->methoddata;
 705         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 706         gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
 707         gss_buffer_desc gssbuf;
 708         OM_uint32 status, ms, flags;
 709         Buffer b;
 710
 711         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 712             recv_tok, &send_tok, &flags);
 713
 714         if (send_tok.length > 0) {
 715                 if (GSS_ERROR(status))
 716                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
 717                 else
 718                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
 719
 720                 packet_put_string(send_tok.value, send_tok.length);
 721                 packet_send();
 722                 gss_release_buffer(&ms, &send_tok);
 723         }
 724
 725         if (status == GSS_S_COMPLETE) {
 726                 /* send either complete or MIC, depending on mechanism */
 727                 if (!(flags & GSS_C_INTEG_FLAG)) {
 728                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
 729                         packet_send();
 730                 } else {
 731                         ssh_gssapi_buildmic(&b, authctxt->server_user,
 732                             authctxt->service, "gssapi-with-mic");
 733
 734                         gssbuf.value = buffer_ptr(&b);
 735                         gssbuf.length = buffer_len(&b);
 736
 737                         status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
 738
 739                         if (!GSS_ERROR(status)) {
 740                                 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
 741                                 packet_put_string(mic.value, mic.length);
 742
 743                                 packet_send();
 744                         }
 745
 746                         buffer_free(&b);
 747                         gss_release_buffer(&ms, &mic);
 748                 }
 749         }
 750
 751         return status;
 752 }
 753
 754 /* ARGSUSED */
 755 void
 756 input_gssapi_response(int type, u_int32_t plen, void *ctxt)
 757 {
 758         Authctxt *authctxt = ctxt;
 759         Gssctxt *gssctxt;
 760         int oidlen;
 761         char *oidv;
 762
 763         if (authctxt == NULL)
 764                 fatal("input_gssapi_response: no authentication context");
 765         gssctxt = authctxt->methoddata;
 766
 767         /* Setup our OID */
 768         oidv = packet_get_string(&oidlen);
 769
 770         if (oidlen <= 2 ||
 771             oidv[0] != SSH_GSS_OIDTYPE ||
 772             oidv[1] != oidlen - 2) {
 773                 free(oidv);
 774                 debug("Badly encoded mechanism OID received");
 775                 userauth(authctxt, NULL);
 776                 return;
 777         }
 778
 779         if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
 780                 fatal("Server returned different OID than expected");
 781
 782         packet_check_eom();
 783
 784         free(oidv);
 785
 786         if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) {
 787                 /* Start again with next method on list */
 788                 debug("Trying to start again");
 789                 userauth(authctxt, NULL);
 790                 return;
 791         }
 792 }
 793
 794 /* ARGSUSED */
 795 void
 796 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
 797 {
 798         Authctxt *authctxt = ctxt;
 799         gss_buffer_desc recv_tok;
 800         OM_uint32 status;
 801         u_int slen;
 802
 803         if (authctxt == NULL)
 804                 fatal("input_gssapi_response: no authentication context");
 805
 806         recv_tok.value = packet_get_string(&slen);
 807         recv_tok.length = slen; /* safe typecast */
 808
 809         packet_check_eom();
 810
 811         status = process_gssapi_token(ctxt, &recv_tok);
 812
 813         free(recv_tok.value);
 814
 815         if (GSS_ERROR(status)) {
 816                 /* Start again with the next method in the list */
 817                 userauth(authctxt, NULL);
 818                 return;
 819         }
 820 }
 821
 822 /* ARGSUSED */
 823 void
 824 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
 825 {
 826         Authctxt *authctxt = ctxt;
 827         Gssctxt *gssctxt;
 828         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 829         gss_buffer_desc recv_tok;
 830         OM_uint32 ms;
 831         u_int len;
 832
 833         if (authctxt == NULL)
 834                 fatal("input_gssapi_response: no authentication context");
 835         gssctxt = authctxt->methoddata;
 836
 837         recv_tok.value = packet_get_string(&len);
 838         recv_tok.length = len;
 839
 840         packet_check_eom();
 841
 842         /* Stick it into GSSAPI and see what it says */
 843         (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 844             &recv_tok, &send_tok, NULL);
 845
 846         free(recv_tok.value);
 847         gss_release_buffer(&ms, &send_tok);
 848
 849         /* Server will be returning a failed packet after this one */
 850 }
 851
 852 /* ARGSUSED */
 853 void
 854 input_gssapi_error(int type, u_int32_t plen, void *ctxt)
 855 {
 856         char *msg;
 857         char *lang;
 858
 859         /* maj */(void)packet_get_int();
 860         /* min */(void)packet_get_int();
 861         msg=packet_get_string(NULL);
 862         lang=packet_get_string(NULL);
 863
 864         packet_check_eom();
 865
 866         debug("Server GSSAPI Error:\n%s", msg);
 867         free(msg);
 868         free(lang);
 869 }
 870 #endif /* GSSAPI */
 871
 872 int
 873 userauth_none(Authctxt *authctxt)
 874 {
 875         /* initial userauth request */
 876         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 877         packet_put_cstring(authctxt->server_user);
 878         packet_put_cstring(authctxt->service);
 879         packet_put_cstring(authctxt->method->name);
 880         packet_send();
 881         return 1;
 882 }
 883
 884 int
 885 userauth_passwd(Authctxt *authctxt)
 886 {
 887         static int attempt = 0;
 888         char prompt[150];
 889         char *password;
 890         const char *host = options.host_key_alias ?  options.host_key_alias :
 891             authctxt->host;
 892
 893         if (attempt++ >= options.number_of_password_prompts)
 894                 return 0;
 895
 896         if (attempt != 1)
 897                 error("Permission denied, please try again.");
 898
 899         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
 900             authctxt->server_user, host);
 901         password = read_passphrase(prompt, 0);
 902         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 903         packet_put_cstring(authctxt->server_user);
 904         packet_put_cstring(authctxt->service);
 905         packet_put_cstring(authctxt->method->name);
 906         packet_put_char(0);
 907         packet_put_cstring(password);
 908         explicit_bzero(password, strlen(password));
 909         free(password);
 910         packet_add_padding(64);
 911         packet_send();
 912
 913         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 914             &input_userauth_passwd_changereq);
 915
 916         return 1;
 917 }
 918
 919 /*
 920  * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
 921  */
 922 /* ARGSUSED */
 923 void
 924 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
 925 {
 926         Authctxt *authctxt = ctxt;
 927         char *info, *lang, *password = NULL, *retype = NULL;
 928         char prompt[150];
 929         const char *host = options.host_key_alias ? options.host_key_alias :
 930             authctxt->host;
 931
 932         debug2("input_userauth_passwd_changereq");
 933
 934         if (authctxt == NULL)
 935                 fatal("input_userauth_passwd_changereq: "
 936                     "no authentication context");
 937
 938         info = packet_get_string(NULL);
 939         lang = packet_get_string(NULL);
 940         if (strlen(info) > 0)
 941                 logit("%s", info);
 942         free(info);
 943         free(lang);
 944         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 945         packet_put_cstring(authctxt->server_user);
 946         packet_put_cstring(authctxt->service);
 947         packet_put_cstring(authctxt->method->name);
 948         packet_put_char(1);                     /* additional info */
 949         snprintf(prompt, sizeof(prompt),
 950             "Enter %.30s@%.128s's old password: ",
 951             authctxt->server_user, host);
 952         password = read_passphrase(prompt, 0);
 953         packet_put_cstring(password);
 954         explicit_bzero(password, strlen(password));
 955         free(password);
 956         password = NULL;
 957         while (password == NULL) {
 958                 snprintf(prompt, sizeof(prompt),
 959                     "Enter %.30s@%.128s's new password: ",
 960                     authctxt->server_user, host);
 961                 password = read_passphrase(prompt, RP_ALLOW_EOF);
 962                 if (password == NULL) {
 963                         /* bail out */
 964                         return;
 965                 }
 966                 snprintf(prompt, sizeof(prompt),
 967                     "Retype %.30s@%.128s's new password: ",
 968                     authctxt->server_user, host);
 969                 retype = read_passphrase(prompt, 0);
 970                 if (strcmp(password, retype) != 0) {
 971                         explicit_bzero(password, strlen(password));
 972                         free(password);
 973                         logit("Mismatch; try again, EOF to quit.");
 974                         password = NULL;
 975                 }
 976                 explicit_bzero(retype, strlen(retype));
 977                 free(retype);
 978         }
 979         packet_put_cstring(password);
 980         explicit_bzero(password, strlen(password));
 981         free(password);
 982         packet_add_padding(64);
 983         packet_send();
 984
 985         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 986             &input_userauth_passwd_changereq);
 987 }
 988
 989 static int
 990 identity_sign(Identity *id, u_char **sigp, u_int *lenp,
 991     u_char *data, u_int datalen)
 992 {
 993         Key *prv;
 994         int ret;
 995
 996         /* the agent supports this key */
 997         if (id->ac)
 998                 return (ssh_agent_sign(id->ac, id->key, sigp, lenp,
 999                     data, datalen));
1000         /*
1001          * we have already loaded the private key or
1002          * the private key is stored in external hardware
1003          */
1004         if (id->isprivate || (id->key->flags & KEY_FLAG_EXT))
1005                 return (key_sign(id->key, sigp, lenp, data, datalen));
1006         /* load the private key from the file */
1007         if ((prv = load_identity_file(id->filename, id->userprovided)) == NULL)
1008                 return (-1);
1009         ret = key_sign(prv, sigp, lenp, data, datalen);
1010         key_free(prv);
1011         return (ret);
1012 }
1013
1014 static int
1015 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
1016 {
1017         Buffer b;
1018         u_char *blob, *signature;
1019         u_int bloblen, slen;
1020         u_int skip = 0;
1021         int ret = -1;
1022         int have_sig = 1;
1023         char *fp;
1024
1025         fp = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
1026         debug3("sign_and_send_pubkey: %s %s", key_type(id->key), fp);
1027         free(fp);
1028
1029         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1030                 /* we cannot handle this key */
1031                 debug3("sign_and_send_pubkey: cannot handle key");
1032                 return 0;
1033         }
1034         /* data to be signed */
1035         buffer_init(&b);
1036         if (datafellows & SSH_OLD_SESSIONID) {
1037                 buffer_append(&b, session_id2, session_id2_len);
1038                 skip = session_id2_len;
1039         } else {
1040                 buffer_put_string(&b, session_id2, session_id2_len);
1041                 skip = buffer_len(&b);
1042         }
1043         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1044         buffer_put_cstring(&b, authctxt->server_user);
1045         buffer_put_cstring(&b,
1046             datafellows & SSH_BUG_PKSERVICE ?
1047             "ssh-userauth" :
1048             authctxt->service);
1049         if (datafellows & SSH_BUG_PKAUTH) {
1050                 buffer_put_char(&b, have_sig);
1051         } else {
1052                 buffer_put_cstring(&b, authctxt->method->name);
1053                 buffer_put_char(&b, have_sig);
1054                 buffer_put_cstring(&b, key_ssh_name(id->key));
1055         }
1056         buffer_put_string(&b, blob, bloblen);
1057
1058         /* generate signature */
1059         ret = identity_sign(id, &signature, &slen,
1060             buffer_ptr(&b), buffer_len(&b));
1061         if (ret == -1) {
1062                 free(blob);
1063                 buffer_free(&b);
1064                 return 0;
1065         }
1066 #ifdef DEBUG_PK
1067         buffer_dump(&b);
1068 #endif
1069         if (datafellows & SSH_BUG_PKSERVICE) {
1070                 buffer_clear(&b);
1071                 buffer_append(&b, session_id2, session_id2_len);
1072                 skip = session_id2_len;
1073                 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1074                 buffer_put_cstring(&b, authctxt->server_user);
1075                 buffer_put_cstring(&b, authctxt->service);
1076                 buffer_put_cstring(&b, authctxt->method->name);
1077                 buffer_put_char(&b, have_sig);
1078                 if (!(datafellows & SSH_BUG_PKAUTH))
1079                         buffer_put_cstring(&b, key_ssh_name(id->key));
1080                 buffer_put_string(&b, blob, bloblen);
1081         }
1082         free(blob);
1083
1084         /* append signature */
1085         buffer_put_string(&b, signature, slen);
1086         free(signature);
1087
1088         /* skip session id and packet type */
1089         if (buffer_len(&b) < skip + 1)
1090                 fatal("userauth_pubkey: internal error");
1091         buffer_consume(&b, skip + 1);
1092
1093         /* put remaining data from buffer into packet */
1094         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1095         packet_put_raw(buffer_ptr(&b), buffer_len(&b));
1096         buffer_free(&b);
1097         packet_send();
1098
1099         return 1;
1100 }
1101
1102 static int
1103 send_pubkey_test(Authctxt *authctxt, Identity *id)
1104 {
1105         u_char *blob;
1106         u_int bloblen, have_sig = 0;
1107
1108         debug3("send_pubkey_test");
1109
1110         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1111                 /* we cannot handle this key */
1112                 debug3("send_pubkey_test: cannot handle key");
1113                 return 0;
1114         }
1115         /* register callback for USERAUTH_PK_OK message */
1116         dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1117
1118         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1119         packet_put_cstring(authctxt->server_user);
1120         packet_put_cstring(authctxt->service);
1121         packet_put_cstring(authctxt->method->name);
1122         packet_put_char(have_sig);
1123         if (!(datafellows & SSH_BUG_PKAUTH))
1124                 packet_put_cstring(key_ssh_name(id->key));
1125         packet_put_string(blob, bloblen);
1126         free(blob);
1127         packet_send();
1128         return 1;
1129 }
1130
1131 static Key *
1132 load_identity_file(char *filename, int userprovided)
1133 {
1134         Key *private;
1135         char prompt[300], *passphrase;
1136         int perm_ok = 0, quit, i;
1137         struct stat st;
1138
1139         if (stat(filename, &st) < 0) {
1140                 (userprovided ? logit : debug3)("no such identity: %s: %s",
1141                     filename, strerror(errno));
1142                 return NULL;
1143         }
1144         private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok);
1145         if (!perm_ok) {
1146                 if (private != NULL)
1147                         key_free(private);
1148                 return NULL;
1149         }
1150         if (private == NULL) {
1151                 if (options.batch_mode)
1152                         return NULL;
1153                 snprintf(prompt, sizeof prompt,
1154                     "Enter passphrase for key '%.100s': ", filename);
1155                 for (i = 0; i < options.number_of_password_prompts; i++) {
1156                         passphrase = read_passphrase(prompt, 0);
1157                         if (strcmp(passphrase, "") != 0) {
1158                                 private = key_load_private_type(KEY_UNSPEC,
1159                                     filename, passphrase, NULL, NULL);
1160                                 quit = 0;
1161                         } else {
1162                                 debug2("no passphrase given, try next key");
1163                                 quit = 1;
1164                         }
1165                         explicit_bzero(passphrase, strlen(passphrase));
1166                         free(passphrase);
1167                         if (private != NULL || quit)
1168                                 break;
1169                         debug2("bad passphrase given, try again...");
1170                 }
1171         }
1172         return private;
1173 }
1174
1175 /*
1176  * try keys in the following order:
1177  *      1. agent keys that are found in the config file
1178  *      2. other agent keys
1179  *      3. keys that are only listed in the config file
1180  */
1181 static void
1182 pubkey_prepare(Authctxt *authctxt)
1183 {
1184         Identity *id, *id2, *tmp;
1185         Idlist agent, files, *preferred;
1186         Key *key;
1187         AuthenticationConnection *ac;
1188         char *comment;
1189         int i, found;
1190
1191         TAILQ_INIT(&agent);     /* keys from the agent */
1192         TAILQ_INIT(&files);     /* keys from the config file */
1193         preferred = &authctxt->keys;
1194         TAILQ_INIT(preferred);  /* preferred order of keys */
1195
1196         /* list of keys stored in the filesystem and PKCS#11 */
1197         for (i = 0; i < options.num_identity_files; i++) {
1198                 key = options.identity_keys[i];
1199                 if (key && key->type == KEY_RSA1)
1200                         continue;
1201                 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER)
1202                         continue;
1203                 options.identity_keys[i] = NULL;
1204                 id = xcalloc(1, sizeof(*id));
1205                 id->key = key;
1206                 id->filename = xstrdup(options.identity_files[i]);
1207                 id->userprovided = options.identity_file_userprovided[i];
1208                 TAILQ_INSERT_TAIL(&files, id, next);
1209         }
1210         /* Prefer PKCS11 keys that are explicitly listed */
1211         TAILQ_FOREACH_SAFE(id, &files, next, tmp) {
1212                 if (id->key == NULL || (id->key->flags & KEY_FLAG_EXT) == 0)
1213                         continue;
1214                 found = 0;
1215                 TAILQ_FOREACH(id2, &files, next) {
1216                         if (id2->key == NULL ||
1217                             (id2->key->flags & KEY_FLAG_EXT) != 0)
1218                                 continue;
1219                         if (key_equal(id->key, id2->key)) {
1220                                 TAILQ_REMOVE(&files, id, next);
1221                                 TAILQ_INSERT_TAIL(preferred, id, next);
1222                                 found = 1;
1223                                 break;
1224                         }
1225                 }
1226                 /* If IdentitiesOnly set and key not found then don't use it */
1227                 if (!found && options.identities_only) {
1228                         TAILQ_REMOVE(&files, id, next);
1229                         explicit_bzero(id, sizeof(*id));
1230                         free(id);
1231                 }
1232         }
1233         /* list of keys supported by the agent */
1234         if ((ac = ssh_get_authentication_connection())) {
1235                 for (key = ssh_get_first_identity(ac, &comment, 2);
1236                     key != NULL;
1237                     key = ssh_get_next_identity(ac, &comment, 2)) {
1238                         found = 0;
1239                         TAILQ_FOREACH(id, &files, next) {
1240                                 /* agent keys from the config file are preferred */
1241                                 if (key_equal(key, id->key)) {
1242                                         key_free(key);
1243                                         free(comment);
1244                                         TAILQ_REMOVE(&files, id, next);
1245                                         TAILQ_INSERT_TAIL(preferred, id, next);
1246                                         id->ac = ac;
1247                                         found = 1;
1248                                         break;
1249                                 }
1250                         }
1251                         if (!found && !options.identities_only) {
1252                                 id = xcalloc(1, sizeof(*id));
1253                                 id->key = key;
1254                                 id->filename = comment;
1255                                 id->ac = ac;
1256                                 TAILQ_INSERT_TAIL(&agent, id, next);
1257                         }
1258                 }
1259                 /* append remaining agent keys */
1260                 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1261                         TAILQ_REMOVE(&agent, id, next);
1262                         TAILQ_INSERT_TAIL(preferred, id, next);
1263                 }
1264                 authctxt->agent = ac;
1265         }
1266         /* append remaining keys from the config file */
1267         for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1268                 TAILQ_REMOVE(&files, id, next);
1269                 TAILQ_INSERT_TAIL(preferred, id, next);
1270         }
1271         TAILQ_FOREACH(id, preferred, next) {
1272                 debug2("key: %s (%p),%s", id->filename, id->key,
1273                     id->userprovided ? " explicit" : "");
1274         }
1275 }
1276
1277 static void
1278 pubkey_cleanup(Authctxt *authctxt)
1279 {
1280         Identity *id;
1281
1282         if (authctxt->agent != NULL)
1283                 ssh_close_authentication_connection(authctxt->agent);
1284         for (id = TAILQ_FIRST(&authctxt->keys); id;
1285             id = TAILQ_FIRST(&authctxt->keys)) {
1286                 TAILQ_REMOVE(&authctxt->keys, id, next);
1287                 if (id->key)
1288                         key_free(id->key);
1289                 free(id->filename);
1290                 free(id);
1291         }
1292 }
1293
1294 int
1295 userauth_pubkey(Authctxt *authctxt)
1296 {
1297         Identity *id;
1298         int sent = 0;
1299
1300         while ((id = TAILQ_FIRST(&authctxt->keys))) {
1301                 if (id->tried++)
1302                         return (0);
1303                 /* move key to the end of the queue */
1304                 TAILQ_REMOVE(&authctxt->keys, id, next);
1305                 TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1306                 /*
1307                  * send a test message if we have the public key. for
1308                  * encrypted keys we cannot do this and have to load the
1309                  * private key instead
1310                  */
1311                 if (id->key != NULL) {
1312                         if (key_type_plain(id->key->type) == KEY_RSA &&
1313                             (datafellows & SSH_BUG_RSASIGMD5) != 0) {
1314                                 debug("Skipped %s key %s for RSA/MD5 server",
1315                                     key_type(id->key), id->filename);
1316                         } else if (id->key->type != KEY_RSA1) {
1317                                 debug("Offering %s public key: %s",
1318                                     key_type(id->key), id->filename);
1319                                 sent = send_pubkey_test(authctxt, id);
1320                         }
1321                 } else {
1322                         debug("Trying private key: %s", id->filename);
1323                         id->key = load_identity_file(id->filename,
1324                             id->userprovided);
1325                         if (id->key != NULL) {
1326                                 id->isprivate = 1;
1327                                 if (key_type_plain(id->key->type) == KEY_RSA &&
1328                                     (datafellows & SSH_BUG_RSASIGMD5) != 0) {
1329                                         debug("Skipped %s key %s for RSA/MD5 "
1330                                             "server", key_type(id->key),
1331                                             id->filename);
1332                                 } else {
1333                                         sent = sign_and_send_pubkey(
1334                                             authctxt, id);
1335                                 }
1336                                 key_free(id->key);
1337                                 id->key = NULL;
1338                         }
1339                 }
1340                 if (sent)
1341                         return (sent);
1342         }
1343         return (0);
1344 }
1345
1346 /*
1347  * Send userauth request message specifying keyboard-interactive method.
1348  */
1349 int
1350 userauth_kbdint(Authctxt *authctxt)
1351 {
1352         static int attempt = 0;
1353
1354         if (attempt++ >= options.number_of_password_prompts)
1355                 return 0;
1356         /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1357         if (attempt > 1 && !authctxt->info_req_seen) {
1358                 debug3("userauth_kbdint: disable: no info_req_seen");
1359                 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1360                 return 0;
1361         }
1362
1363         debug2("userauth_kbdint");
1364         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1365         packet_put_cstring(authctxt->server_user);
1366         packet_put_cstring(authctxt->service);
1367         packet_put_cstring(authctxt->method->name);
1368         packet_put_cstring("");                                 /* lang */
1369         packet_put_cstring(options.kbd_interactive_devices ?
1370             options.kbd_interactive_devices : "");
1371         packet_send();
1372
1373         dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1374         return 1;
1375 }
1376
1377 /*
1378  * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1379  */
1380 void
1381 input_userauth_info_req(int type, u_int32_t seq, void *ctxt)
1382 {
1383         Authctxt *authctxt = ctxt;
1384         char *name, *inst, *lang, *prompt, *response;
1385         u_int num_prompts, i;
1386         int echo = 0;
1387
1388         debug2("input_userauth_info_req");
1389
1390         if (authctxt == NULL)
1391                 fatal("input_userauth_info_req: no authentication context");
1392
1393         authctxt->info_req_seen = 1;
1394
1395         name = packet_get_string(NULL);
1396         inst = packet_get_string(NULL);
1397         lang = packet_get_string(NULL);
1398         if (strlen(name) > 0)
1399                 logit("%s", name);
1400         if (strlen(inst) > 0)
1401                 logit("%s", inst);
1402         free(name);
1403         free(inst);
1404         free(lang);
1405
1406         num_prompts = packet_get_int();
1407         /*
1408          * Begin to build info response packet based on prompts requested.
1409          * We commit to providing the correct number of responses, so if
1410          * further on we run into a problem that prevents this, we have to
1411          * be sure and clean this up and send a correct error response.
1412          */
1413         packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
1414         packet_put_int(num_prompts);
1415
1416         debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1417         for (i = 0; i < num_prompts; i++) {
1418                 prompt = packet_get_string(NULL);
1419                 echo = packet_get_char();
1420
1421                 response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1422
1423                 packet_put_cstring(response);
1424                 explicit_bzero(response, strlen(response));
1425                 free(response);
1426                 free(prompt);
1427         }
1428         packet_check_eom(); /* done with parsing incoming message. */
1429
1430         packet_add_padding(64);
1431         packet_send();
1432 }
1433
1434 static int
1435 ssh_keysign(Key *key, u_char **sigp, u_int *lenp,
1436     u_char *data, u_int datalen)
1437 {
1438         Buffer b;
1439         struct stat st;
1440         pid_t pid;
1441         int to[2], from[2], status, version = 2;
1442
1443         debug2("ssh_keysign called");
1444
1445         if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
1446                 error("ssh_keysign: not installed: %s", strerror(errno));
1447                 return -1;
1448         }
1449         if (fflush(stdout) != 0)
1450                 error("ssh_keysign: fflush: %s", strerror(errno));
1451         if (pipe(to) < 0) {
1452                 error("ssh_keysign: pipe: %s", strerror(errno));
1453                 return -1;
1454         }
1455         if (pipe(from) < 0) {
1456                 error("ssh_keysign: pipe: %s", strerror(errno));
1457                 return -1;
1458         }
1459         if ((pid = fork()) < 0) {
1460                 error("ssh_keysign: fork: %s", strerror(errno));
1461                 return -1;
1462         }
1463         if (pid == 0) {
1464                 /* keep the socket on exec */
1465                 fcntl(packet_get_connection_in(), F_SETFD, 0);
1466                 permanently_drop_suid(getuid());
1467                 close(from[0]);
1468                 if (dup2(from[1], STDOUT_FILENO) < 0)
1469                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1470                 close(to[1]);
1471                 if (dup2(to[0], STDIN_FILENO) < 0)
1472                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1473                 close(from[1]);
1474                 close(to[0]);
1475                 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0);
1476                 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN,
1477                     strerror(errno));
1478         }
1479         close(from[1]);
1480         close(to[0]);
1481
1482         buffer_init(&b);
1483         buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */
1484         buffer_put_string(&b, data, datalen);
1485         if (ssh_msg_send(to[1], version, &b) == -1)
1486                 fatal("ssh_keysign: couldn't send request");
1487
1488         if (ssh_msg_recv(from[0], &b) < 0) {
1489                 error("ssh_keysign: no reply");
1490                 buffer_free(&b);
1491                 return -1;
1492         }
1493         close(from[0]);
1494         close(to[1]);
1495
1496         while (waitpid(pid, &status, 0) < 0)
1497                 if (errno != EINTR)
1498                         break;
1499
1500         if (buffer_get_char(&b) != version) {
1501                 error("ssh_keysign: bad version");
1502                 buffer_free(&b);
1503                 return -1;
1504         }
1505         *sigp = buffer_get_string(&b, lenp);
1506         buffer_free(&b);
1507
1508         return 0;
1509 }
1510
1511 int
1512 userauth_hostbased(Authctxt *authctxt)
1513 {
1514         Key *private = NULL;
1515         Sensitive *sensitive = authctxt->sensitive;
1516         Buffer b;
1517         u_char *signature, *blob;
1518         char *chost, *pkalg, *p;
1519         const char *service;
1520         u_int blen, slen;
1521         int ok, i, found = 0;
1522
1523         /* check for a useful key */
1524         for (i = 0; i < sensitive->nkeys; i++) {
1525                 private = sensitive->keys[i];
1526                 if (private && private->type != KEY_RSA1) {
1527                         found = 1;
1528                         /* we take and free the key */
1529                         sensitive->keys[i] = NULL;
1530                         break;
1531                 }
1532         }
1533         if (!found) {
1534                 debug("No more client hostkeys for hostbased authentication.");
1535                 return 0;
1536         }
1537         if (key_to_blob(private, &blob, &blen) == 0) {
1538                 key_free(private);
1539                 return 0;
1540         }
1541         /* figure out a name for the client host */
1542         p = get_local_name(packet_get_connection_in());
1543         if (p == NULL) {
1544                 error("userauth_hostbased: cannot get local ipaddr/name");
1545                 key_free(private);
1546                 free(blob);
1547                 return 0;
1548         }
1549         xasprintf(&chost, "%s.", p);
1550         debug2("userauth_hostbased: chost %s", chost);
1551         free(p);
1552
1553         service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
1554             authctxt->service;
1555         pkalg = xstrdup(key_ssh_name(private));
1556         buffer_init(&b);
1557         /* construct data */
1558         buffer_put_string(&b, session_id2, session_id2_len);
1559         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1560         buffer_put_cstring(&b, authctxt->server_user);
1561         buffer_put_cstring(&b, service);
1562         buffer_put_cstring(&b, authctxt->method->name);
1563         buffer_put_cstring(&b, pkalg);
1564         buffer_put_string(&b, blob, blen);
1565         buffer_put_cstring(&b, chost);
1566         buffer_put_cstring(&b, authctxt->local_user);
1567 #ifdef DEBUG_PK
1568         buffer_dump(&b);
1569 #endif
1570         if (sensitive->external_keysign)
1571                 ok = ssh_keysign(private, &signature, &slen,
1572                     buffer_ptr(&b), buffer_len(&b));
1573         else
1574                 ok = key_sign(private, &signature, &slen,
1575                     buffer_ptr(&b), buffer_len(&b));
1576         key_free(private);
1577         buffer_free(&b);
1578         if (ok != 0) {
1579                 error("key_sign failed");
1580                 free(chost);
1581                 free(pkalg);
1582                 free(blob);
1583                 return 0;
1584         }
1585         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1586         packet_put_cstring(authctxt->server_user);
1587         packet_put_cstring(authctxt->service);
1588         packet_put_cstring(authctxt->method->name);
1589         packet_put_cstring(pkalg);
1590         packet_put_string(blob, blen);
1591         packet_put_cstring(chost);
1592         packet_put_cstring(authctxt->local_user);
1593         packet_put_string(signature, slen);
1594         explicit_bzero(signature, slen);
1595         free(signature);
1596         free(chost);
1597         free(pkalg);
1598         free(blob);
1599
1600         packet_send();
1601         return 1;
1602 }
1603
1604 /* find auth method */
1605
1606 /*
1607  * given auth method name, if configurable options permit this method fill
1608  * in auth_ident field and return true, otherwise return false.
1609  */
1610 static int
1611 authmethod_is_enabled(Authmethod *method)
1612 {
1613         if (method == NULL)
1614                 return 0;
1615         /* return false if options indicate this method is disabled */
1616         if  (method->enabled == NULL || *method->enabled == 0)
1617                 return 0;
1618         /* return false if batch mode is enabled but method needs interactive mode */
1619         if  (method->batch_flag != NULL && *method->batch_flag != 0)
1620                 return 0;
1621         return 1;
1622 }
1623
1624 static Authmethod *
1625 authmethod_lookup(const char *name)
1626 {
1627         Authmethod *method = NULL;
1628         if (name != NULL)
1629                 for (method = authmethods; method->name != NULL; method++)
1630                         if (strcmp(name, method->name) == 0)
1631                                 return method;
1632         debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1633         return NULL;
1634 }
1635
1636 /* XXX internal state */
1637 static Authmethod *current = NULL;
1638 static char *supported = NULL;
1639 static char *preferred = NULL;
1640
1641 /*
1642  * Given the authentication method list sent by the server, return the
1643  * next method we should try.  If the server initially sends a nil list,
1644  * use a built-in default list.
1645  */
1646 static Authmethod *
1647 authmethod_get(char *authlist)
1648 {
1649         char *name = NULL;
1650         u_int next;
1651
1652         /* Use a suitable default if we're passed a nil list.  */
1653         if (authlist == NULL || strlen(authlist) == 0)
1654                 authlist = options.preferred_authentications;
1655
1656         if (supported == NULL || strcmp(authlist, supported) != 0) {
1657                 debug3("start over, passed a different list %s", authlist);
1658                 free(supported);
1659                 supported = xstrdup(authlist);
1660                 preferred = options.preferred_authentications;
1661                 debug3("preferred %s", preferred);
1662                 current = NULL;
1663         } else if (current != NULL && authmethod_is_enabled(current))
1664                 return current;
1665
1666         for (;;) {
1667                 if ((name = match_list(preferred, supported, &next)) == NULL) {
1668                         debug("No more authentication methods to try.");
1669                         current = NULL;
1670                         return NULL;
1671                 }
1672                 preferred += next;
1673                 debug3("authmethod_lookup %s", name);
1674                 debug3("remaining preferred: %s", preferred);
1675                 if ((current = authmethod_lookup(name)) != NULL &&
1676                     authmethod_is_enabled(current)) {
1677                         debug3("authmethod_is_enabled %s", name);
1678                         debug("Next authentication method: %s", name);
1679                         free(name);
1680                         return current;
1681                 }
1682                 free(name);
1683         }
1684 }
1685
1686 static char *
1687 authmethods_get(void)
1688 {
1689         Authmethod *method = NULL;
1690         Buffer b;
1691         char *list;
1692
1693         buffer_init(&b);
1694         for (method = authmethods; method->name != NULL; method++) {
1695                 if (authmethod_is_enabled(method)) {
1696                         if (buffer_len(&b) > 0)
1697                                 buffer_append(&b, ",", 1);
1698                         buffer_append(&b, method->name, strlen(method->name));
1699                 }
1700         }
1701         buffer_append(&b, "\0", 1);
1702         list = xstrdup(buffer_ptr(&b));
1703         buffer_free(&b);
1704         return list;
1705 }
1706